1 ITS 1 Edition 8/May 2007 Interface Technical Specifications for the France Telecom s network Directive 1999/5/EC Analogue subscriber interface characteristics Summary: This document describes the analogue subscriber interface characteristics, interface Z, for the France Telecom network Warning : "Only the French text is considered as valid ; therefore France Telecom accepts no responsibility or liability whatsoever with regard to any information or data referred to in this document". France Telecom 6, Place d Alleray Paris Cedex 15 France
2 Notice Information enclosed in this document is at terminal equipment manufacturers' disposal, pursuant to Directive 1999/5/EC of the European Parliament and of the Council of 9 March 1999 on radio equipment and telecommunications terminal equipment and the mutual recognition of their conformity. According to Directive 1999/5/EC and specially Article 4.2, France Telecom reserves the right to modify or complement the information contained in this document in order to update the interface technical specifications and to allow the creation of telecommunication terminal equipments capable of using the services provided by the corresponding interfaces. France Telecom can be held responsible neither for non-operation or poor operation of a terminal equipment, if the equipment complies with this specification, nor for any damage resulting from the use or misuse of the information contained in this document, towards whoever it be. Provision of these technical specifications results in no transfer of rights, no granting of license on any intellectual property right, belonging to France Telecom. France Telecom holds exclusive rights on France Telecom brands mentioned in this document. France Telecom further points out users' attention on the following points: 1. timer values are indicative and can be subject to modification, 2. due to various technical constraints, some services or service options may not be available on some interfaces, 3. the fact that a service not yet commercially open is described in this document can in no case be considered as a binding commitment on France Telecom part to actually open this service.
3 Contents 1. GENERAL COMMENTS INTRODUCTION DEFINITIONS AND ABBREVIATIONS REFERENCE DOCUMENTS BASIC CHARACTERISTICS INTRODUCTION CONNECTING MODE TO THE NETWORK POWER SUPPLY POLARITY CONDITIONS IN QUIESCENT STATE RINGING DETECTION CONDITIONS ESTABLISHMENT OF LOOP STATE CONVERSATION STATE DIALLING CONDITIONS END OF LOOP CONDITION ADDITIONAL CHARACTERISTICS REGISTER RECALL TRANSMISSION OF METER PULSES POLARITY INVERSION NEUTRALISATION OF ECHO TREATMENT DEVICES MONITORING SIGNALS OVERVOLTAGE ON LINE GLOSSARY HISTORY APPENDICES...23
4 General comments 1.1 Introduction This document describes the characteristics related to the physical interface of the network, except for supplementary services information which is described in a separate document (Cf document ). The document is divided into two technical parts. The first part, entitled Basic characteristics, describes the characteristics of the network relating to the basic service according to ETSI TBR 21 approach . The second part, entitled Additional characteristics describes the physical characteristics of the network not covered by TBR 21. This document refers as far as possible to the relevant published standards, and only describes the used options and particularities of these standards. The characteristics are defined at the network termination point (NTP). To design terminal equipment to be connected in parallel or series on a single subscriber line, it is appropriate to refer to ETSI Guide EG , taking into account that the network can support 100 Loading Units (LU). 1.2 Definitions and abbreviations Definitions In addition to definitions and abbreviations used in TBR 21, this document uses the following : LF LU Loading Factor Loading Factor corresponding to the part of the network resources used by terminal equipment or group of terminal equipment (terminal installation) when connected to the network termination point (NTP). Cf guide EG . Loading Unit Arbitrary Loading Unit to measure (or evaluate) the loading factor (LF). Cf guide EG  Abbreviations See 4 "Glossary".
5 Reference documents  Directive 1999/5/EC of the European Parliament and Council dated 9 March 1999 concerning hertzian equipment and telecommunications terminal equipment and mutual recognition of its conformity (published in the OFEC on )  TBR 21 (January 1998 Edition) - Terminal equipment (TE); Connection requirements for pan-european approval for connection to the analogue Public Switched Telephone Networks (PSTNs) of TE (excluding TE supporting the voice telephony service) in which network addressing, if provided, is by means of Dual Tone Multi Frequency (DTMF) signalling. French version: Document referenced AFNOR FD Z  TBR 38 (May 1998 Edition) - Public Switched Telephone Network (PSTN) ; Connection requirements for a terminal equipment incorporating an analogue handset function capable of supporting the justified case service when connected to the analogue interface of the PSTN in Europe.  EG Public Switched Telephone Network (PSTN); method of rating terminal equipment so that it can be connected in series and/or in parallel to a Network Termination Point (NTP)  STI 2 Additional services that can be accessed from France Telecom network analogue lines.  EN Terminal equipment (TE); Attachement requirements for pan-european approval for connection to the analogue Public Switched Telephone Networks (PSTNs) of TE supporting the voice telephony service in which network addressing, if provided, is by means of Dual Tone Multi Frequency (DTMF) signalling [7 STI 3 Connection interface to the France Telecom-Ringing-Dial Tone network [8 ETS Attachments to the Public Switched Telephone Network (PSTN); General technical requirements for equipment connected to an analogue subscriber interface in the PSTN (Chapter 5: Calling function) French transposition: Document referenced AFNOR FD Z [9 IEC Connectors for electronic equipment - Part 7-1: Special specification for armoured, 8-channel connectors comprising plugs and bases with common coupling characteristics, with quality assurance.
6 - 3 - [10 IEC Connectors for electronic equipment - Part 7-3: Special specification for armoured, 8-channel connectors comprising plugs and bases, for data transmission at frequencies of up to 100 MHz [11 UTE C Residential wiring for communication networks [12 UTE C Unshielded cables for Grade 1 interior telecommunications installations Special specification for series 298 cables [13 UTE C Shielded cables for Grade 1 residential cables [14 TR Access and Terminals; Analogue Access to Public Telephone Network Advisory Notes to Standards harmonising terminal interface Part 04: Information arising from CEC decisions; Sub-part 1: General loop steady state requirements Note: Standards 4 and 6 are not quoted in the following text. They are indicated in paragraph 1.3 as bibliography.
7 Basic characteristics 2.1 Introduction The analogue subscriber interface to the France Telecom switched telephone network is compatible with terminal equipment that complies with ETSI European Standard TBR 21 (January 1998 edition). The following clauses precise or complement points described in TBR21, in order to allow manufacturers to optimise the adequation of their terminal equipment to France Telecom network. 2.2 Connecting mode to the network Line termination point (LTP) The line termination point is the first physical network access point installed by France Telecom and, in general, located into the subscriber's premises. It is intended to separate the local loop line from the wiring customer (ie installation wiring in the customer premises), in order to allow the subscriber to test the local loop line. This point is materialised in the following way: - by a device called the Indoor Termination Device (ITD):. equipped with a RC module (R = 20 K and C = 2.2 F) called the testing module,. allowing the terminal equipment plug to be plugged related to the type of connector used for wiring the subscriber s installation, either into T-connector, or into CEI connector (see ), while isolating the subscriber s installation wiring, in order to test the local loop line (in normal service, no terminal equipment should be plugged into the ITD), (*). if necessary, equipped with a module to protect against electrical surges. A diagram of the ITD is given in Figure by a 12-pole strip equipped with an RC module (R = 20 K and C = 2.2 F) called the testing module, - by the first telephone socket of the subscriber s installation equipped with an RC module (R = 20 K and C = 2.2 F) that can be used to test the line, - or by a device composed of an interface strip and test points. (*) : The RC testing module is necessary for line tests made from the network when the installation terminals are unplugged.
8 - 5 - CONNECTION NETWORK SIDE Local loop line RC Module Output 1 to the terminal installation access USER CABLING TOWARDS PLUGS Output 2 to the terminal installation access Straps for telephone-like connections Test strip, either T-type or CEI type Note: The test socket allows the terminal equipment plug to be plugged in, at the same time isolating the customer s wiring, in order to test the local loop line (in normal service, no terminal equipment should be plugged into the ITD). Figure Diagram of the ITD with test socket to connect a terminal Network termination points (NTPs) and connecting terminal equipment to the network The two types of NTP connection Except for some types of terminals (eg meter pulse detectors), a terminal is connected using a standard male plug to be plugged into a female socket fixed to the wall and connected, on the network side, to one or more analogue subscriber access lines. The female socket constitutes the Network Terminal Point (NTP).
9 - 6 - Since the end of 2003, France Telecom has only used plugs with IEC bases for new terminal installations. In addition, the technical reference documentation enclosed with agreements between France Telecom and property developers specifies this type of telephone socket. Before the end of 2003, France Telecom used T-sockets for terminal installations. As a result, two types of female sockets can be found at the NTPs of France Telecom public network analogue lines: - T-plugs with 3, 6 or 8 poles (contacts), - sockets with an IEC base. In this document, this type of socket will generally be referred to as an IEC socket. A terminal installation is set up using only one type of socket. An extension to a terminal installation where T- sockets were used is made using a T-socket.
10 NTP with a T socket Description of the T-socket The T-socket may have 3, 6 or 8 poles. The numbering of the poles is described in Appendices 3 and 5 with drawings of the plug: - Appendix 3 contains the drawings for 6-pole plugs. The 3-pole plug has the same body without metal poles 4, 5 and 6 inserted. - Appendix 5 contains the drawings for 8-pole plugs. Female socket Male plug Figure a Front of the female socket and side view of the mal plug with 3 or 6 poles The numbering of the poles in the socket corresponds to the numbering of the poles in the plug. The diagram below indicates the numbering of the poles in the socket or 6-pole female socket 8-pole female socket Figure b Numbering of the poles in a female socket
11 Connection of one or several simple terminals in the same subscriber terminal installation, on the same outgoing LTP (cf ) Subscriber terminal installation with one socket for an LTP (cf ) TE with transmission circuit Ringing detection Dialling way DTMF dialling Loop-disconnect dialling Without ringing detector 1 3 A S B W ith ringing detector unsensitive to the loopdisconnect dialling 1 3 C S D W ith ringing detector sensitive to the loop-disconnect dialling E S F External ringing detector Unsensitive to the loop-diconnect dialling Sensitive to the loop-disconnect dialling G 3 H Transmission circuit Bell or equivalent Loop-disconnect dialling contact Switch hook or equivalent Bell shunt Figure a Wiring diagram for the female socket for a subscriber terminal installation
12 - 9 - The transmission circuit is connected between poles 1 and 3, which give access to the line wires via the switch hook or equivalent. The incorporated or external call receiving circuit is connected to pole 1 of the call detector (e.g. by ringing) and to pole 3 on the capacitator side, as in cases C, D, E, F, G or H. If the call detector is sensitive to the loop disconnect dialling of terminal equipment connected in parallel (e.g. bell tinkling), the point between the capacitator and call detector can be connected to pole 2, as in case E, F or H. Implementation of the RC circuit (R = 20 K and C = 2.2 F) called the testing module, If T-sockets are used for the terminal installation, the RC circuit (test module) is located in the LTP equipment (cf ) or, failing this, in the first socket of the terminal installation wired between poles 1 and 3. A subscriber terminal installation connected via one (or two) network lines, with several sockets on the same LTP (cf ) a Socket Prise 1 1 Socket Prise 22 Line 1 (from Ligne an output 1 of the ITD) (en provenance d'un départ du PTL) B b Vers To les other autres prises sockets avec le in même mode parallel de câblage (mode parallèle) a Line 2 * (from an output Ligne 2 * of the ITD) (en provenance d'un départ du PTL) B b B : RC B network : Circuit for RC testing pour the l'essai linede ligne : Utilisé pour le raccordement à une deuxième ligne d'abonné --- : Used for connecting to a second subscriber s line * : The * extension of the connecting to the network up to 2 lines requires to use a T-socket with 8 poles. : l'extension du raccordement au réseau à 2 lignes nécessite l'emploi d'une prise en T avec 8 plots Figure b Socket wiring diagram for a subscriber terminal installation connected via one (or two) network lines, with several sockets on the same LTP.
13 The female socket pole allocation is as follows: Pole N 8-pole female socket allocation 1 a" wire on line 1 2 Anti-tinkling line 1 3 b" wire on line 1 4 not used 5 not used 6 a" wire on line 2 7 Anti-tinkling line 2 8 b" wire on line 2 The male plug pole allocation is as follows: Asssignment Pole N 3-pole male plug 6-pole male plug 8-pole male plug 1 a wire a wire a" wire on line 1 2 shunt wire (*) shunt wire (*) shunt wire (*) on line 1 3 b wire b wire b" wire on line 1 4 not used not used 5 not used not used 6 not used a" wire on line 2 7 shunt wire (*) on line 2 8 b" wire on line 2 (*): The purpose of the shunt wire is to prevent the bell of a telephone terminal from tinkling due to loop-disconnected dialling on parallel terminal equipment. Use of pole 2 is obsolete since multifrequency dialling and electronic bells not affected by parallel decimal dialling has come into widespread use. Implementation of the RC circuit (R = 20 K and C = 2.2 F) called the testing module : If T-sockets are used for the terminal installation, the RC circuit (test module) is located in the LTP equipment (cf ) or, failing this, in the first socket of the terminal installation as per Figure b.
14 Connection of additional terminal equipment in a subscriber terminal installation An additional single terminal for a switched telephone network line in a subscriber terminal installation is connected by installing an additional female socket wired in parallel mode (see the socket wiring diagram at the figure b). Reminder of last section of 1.1: The characteristics are defined at the network terminal point (NTP). To design terminal equipment to be connected in parallel or series on the same subscriber line, please refer to ETSI Guide EG , taking into account that the network can support 100 Loading Units (LU) NTP with an IEC socket Description of the IEC socket Since the end of 2003, France Telecom has only used sockets with IEC bases for new terminal installations. In addition, the technical reference documentation enclosed with agreements between France Telecom and property developers specifies this type of telephone socket. The wiring for installations with this type of socket is termed multimedia and can be used up to a frequency of 100 Mhz. It complies with the Grade 1 specifications defined in the UTE C [11 guide. The sockets used are sockets with an IEC base. The characteristics of these bases comply with IEC [9 and IEC [10 standards Figure a Base of the IEC socket
15 The 8 contacts of the IEC socket base connectors are allocated in line with the recommendations of the UTE C [11 guide. N of the pair in the network side cable a wire Pair 3 b wire a wire Pair 2 b wire Pair 1 Pair 4 a wire b wire a wire b wire Contact N in the RJ45 base (Main) functions Ethernet (10 and 100 T base) Ethernet (10 and 100 T base) S bus send of an ISDN terminal connected to a basic access S bus receive of an ISDN terminal connected to a basic access Line 1 (analogue line or ISDN basic access) Line 2 (analogue line or ISDN basic access) Table b Allocation of the pairs of the cable on the network side to the IEC socket contacts Connection of one or more simple terminals in the same subscriber terminal installation The terminal installations are star-connected from the customer distribution frame, using the following rule: each branch, a maximum of 45m long, serves one socket constituting a NTP (cf ). There are therefore as many branches as there are NTPs. In general, the customer distribution frame has two interfaces: one interface on the network side which is connected to the ITD (see 2.2.1) and equipped with a set of IEC sockets connected via a patch panel to the distribution frame interface IEC sockets on the terminal installation side, - one interface on the terminal installation side equipped with a set of IEC sockets. The far ends of the wires of all the branches of the terminal installation are connected to this interface so as to be respectively connected to the above-mentioned sockets. The terminal installation is wired using a: - shielded cable (UTE C [13 standard) or unshielded cable (UTE C [12 standard), - with 4 twisted pairs for each branch, - with 0.5 mm diameter copper conductors, the far ends of which are connected to the customer distribution frame socket on the terminal installation side and to the NTP socket on the other.
16 ITD DTI Network Interface side interface côté réseau 1 an départ ITD du output DTI vers towards l'installation terminal installation terminale Sockets Prises CUSTOMER DISTRIBUTION REPARTITEUR CLIENT FRAME Panneau Patch panel de brassage Terminal Interface installation côté side interface installation terminale Sockets Prises Socket Prise Socket Prise Socket Prise Cables with 4 twisted pairs câbles 4 paires torsadées avec conducteur 0,5 mm de diamètre Socket Prise Figure Diagram of a terminal installation with IEC sockets.
17 Power supply polarity Cf TBR 21 (January 1998 Edition) Compliance with the characteristics specified below must be independent of the power supply polarity. Since this polarity inversion is not systematic, it cannot be used by the terminals. 2.4 Conditions in quiescent state Quiescent conditions cover states where the line is not engaged or is in a ringing phase. The subscriber s terminal installation is powered by direct voltage of between 45 V and 54 V Resistance between wires Cf TBR 21 (January 1998 Edition) Conditions at 50 Hz Impedance Cf TBR 21 (January 1998 Edition) Transient response Cf TBR 21 (January 1998 Edition) Direct current Cf TBR 21 (January 1998 Edition) Impedance unbalance about earth Cf TBR 21 (January 1998 Edition) Resistance to earth Cf TBR 21 (January 1998 Edition) 2.5 Ringing detection conditions Cf 4.5 TBR 21 (January 1998 Edition) NOTE: However, as indicated in Note 2, 4.5 of TBR 21 (January 1998 Edition), it is advisable to refer to document  relating to the characteristics of ringing and tones transmitted by the network to ensure proper detection on the France Telecom network Ringing signal linearity In order to prevent the call signal from generating interference on neighbouring lines by cross-talk, any individual frequency component due to possible distortion of the call signal applied to the call receiving terminal, should not exceed the limits indicated by the following mask. This is for a 80 V eff call signal level, a 54 V DC power supply voltage and a line resistance of 230.
18 Establishment of loop state Breaks in the loop Cf TBR 21 (January 1998 Edition) Loop current establishment Cf TBR21 (January 1998 edition) modified by ETSI TR (V june 2003) 2.7 Conversation state Loop characteristics Cf TBR21 (January 1998 edition) modified by ETSI TR (V june 2003) For a terminal compliant with the mask U=f(I) of TBR 21 modified by ETSI TR (V june 2003), in all stable phases of operation (dialling, conversation, on, conversation, waiting and false call) the loop current provided by the network is equal to 15 ma or above Impedance Cf TBR21  (January 1998 Edition) Note: The France Telecom network accepts terminals with complex impedance, compliant with the one described in TBR 21. However, in the event of a short line connection, the network impedance is 600, with a return loss of at least 14 db between 300 and 3400 Hz. However, a limited number of analogue subscriber cards are adapted for complex impedance Sending level limitation Mean sending level Cf TBR 21 (January 1998 Edition) Instantaneous voltage Cf TBR 21 (January 1998 Edition)
19 Sending level in a 10 Hz bandwidth Cf TBR 21 (January 1998 Edition) Sending level above 4.3 khz Cf TBR 21 (January 1998 Edition) Impedance unbalance about earth Longitudinal conversion loss Cf TBR 21 (January 1998 Edition) Output signal balance Cf TBR 21 (January 1998 Edition) Noise This parameter is not specified in TBR 21: please refer to Chapter of TBR 38 (May 1998 Edition) Dialling conditions Automatic dialling Dialling without dial tone detection Cf TBR 21 (January 1998 Edition) Note: The network accepts information via the automatic dialling of a terminal installation without dial tone detection if a timeout has elapsed Dialling with dial tone detection Cf TBR 21 (January 1998 Edition) DTMF signalling Frequency combinations Cf TBR 21 (January 1998 Edition) Signalling level Cf TBR 21 (January 1998 Edition) Unwanted frequency components Cf TBR 21 (January 1998 Edition) Tone duration Cf TBR 21 (January 1998 Edition) Pause duration Cf TBR 21 (January 1998 Edition)
20 Decadic dialling (loop pulsing) The implementation of this function is no longer necessary for terminal operation on the France Telecom network. However, decadic dialling is still accepted, as per Chapter 5 of ETS  Automatically repeated call attempts Cf TBR 21 (January 1998 Edition) 2.9 End of loop condition Transition from a loop condition to quiescent state is taken into account by the network when the value of the loop current stays below 5 ma for more than 500 ms.
21 Additional characteristics 3.1 Register recall Register recall is the opening of a dc loop for a calibrated period of time, presented to the network by the terminal to enable the network to offer certain additional services. The register recall calibrated time opening pulse can be transmitted to the network by manual activation on the terminal or automatically by the terminal itself. In the event of manual action, the opening impulse time must be independent from the length of time the corresponding button is pressed. I (ma) Loop current Loop condition Pre-opening Register recall condition Opening period Post-opening Loop condition period period I 3 I f t b I r I 2 I 1 I m t 1 t 2 t a t 3 t 4 t i t m t t t p Time t (ms) Figure 3.1 Register recall PARAMETERS t m tb tb Im I1 I2 (ms) (ms) (ms) (ma) (ma) (ma) ±
22 Transmission of meter pulses When the function of charging information is applied by the network at the NTP, the network sends to the terminal installation meter pulses. These pulses consist of a 12kHz-rated transversal signal. Characteristics of meter pulses at NTP poles are indicated in the table below. PARAMETERS fmin fmax emin emax (khz) (khz) (mv) (mv) Whatever in the presence or absence of loop current, meter pulses are transmitted during a period of 75ms, as a minimum and 150ms at the maximum, with intervals between them of at least 75ms. In quiescent condition, one or several meter pulse(s) may be transmitted within 2 secs following the line release. 3.3 Polarity inversion Some France Telecom equipment allows inversion of the power supply to the requester s line when the called party picks up the call or on receipt of the answering signal. Since this information is not available throughout the network, it cannot be used by terminals. 3.4 Neutralisation of echo treatment devices Introduction Echo suppressors or cancellers have a tone neutralisation device to ensure that signals crossing it in either direction are no longer modified on receipt of the signals defined below, which are transmitted by some terminals Signal characteristics Echo suppressors or cancellers are neutralised by the terminal equipment in loop condition, transmitting a 2100 Hz 15 Hz tone during a period of secs, at a level between p1 (dbm) and p2 (dbm) measured on a load impedance of Zl ( ), for Vf and Rf DC voltages as specified in Table For automatic answering, the tone must be preceded by a period of silence between 1.8 and 2.5 secs after a dc loop condition has been established, followed by a period of silence of msecs, after which power must be maintained with no signal spacing above 100 msecs, in order to maintain the neutralisation of echo treatment devices. If the terminal equipment has echo cancellers or suppressors to be neutralised at the same time as those on the network, the terminal must then reverse the tone phase at intervals of between 425 and 475 msecs, in order to obtain a phase angle of over degrees in less than 1 msec and a 2100 Hz tone amplitude no more than 3 db lower than its stable state value for a maximum of 400 s. The transmission period must be:
23 less than 2.6 msecs if an answer is received from the calling station. In this case, the 2100 Hz tone may be stopped once an answer has been detected from the calling station during a continuous period of 100 msecs. - over 4 secs but less than 10 secs, in applications where an automatic answering TEUT is permanently assigned to receiving calls transmitted only by acoustic coupling stations, in order to take the reaction time required by the operator to put the telephone handset into contact with the acoustic coupler. Table Neutralisation of echo treatment devices Value required Value required PARAMETERS Test value Test value Test value Test value Test value p1 (dbm) p2 (dbm) Zl ( ) Vf (V) Rf ( ) If (ma) Comment yes Note: The maximum level of the echo canceller neutralisation tone is 3V. 3.5 Monitoring signals The characteristics of ringtones and other tones transmitted by the network are described in document . 3.6 Overvoltage on line Mains electricity in France: The neutral conductor of electrical installations is earthed via the EDF (Electricity Board) transformer located at a varying distance, the potential of which may vary considerably irrespective of the variations supported by the earths of the telecommunications terminal installation and the associated telephone switch sites. The lower limit of voltage taken into consideration by France Telecom for the protection of telecommunications equipment: The value of 10 KV has been adopted as this limit in France Telecom approval specifications for telecommunications terminals. Experimentation has proved this value sufficient.
24 Glossary IEC ITD DTMF LF LU TEUT NTP PSTN LTP NTP PSTN TE UTE C International Electrotechnical Commission Indoor Termination Device Dual Tone Multi Frequency signalling Loading Factor Loading Unit Terminal Equipment Under Test Network Termination Point Public Switched Telephone Network Line Termination Point Network Termination Point Public Switched Telephone Network Terminal Equipment Union Technique de l Electricité et de la Communication (Technical Electricity and Communication Union)
25 History Edition Date Comments 1 March 2000 Initial version. 2 October 2000 Correction of errors in the wiring diagram and format. 3 December 2001 Modification of (Line Terminal Point) with specific addition of the ITD, addition of the reference  and modification of September 2002 Addition of appendices for 6 containing drawings of the NTP component, the T-socket, and corresponding terminal plug. 5 April 2004 Introduction of a second type of NTP for the France Telecom network analogue subscriber interface. This new type of NTP is based on an IEC socket. 6 December 2005 Modifications to 1.3 (Reference documents), (Loop characteristics) and 3.2 (Retransmission of metering). 7 June 2006 Modifications to 3.2 (Transmission of meter pulses). 8 May 2007 Modifications to 2.2.1(Line termination point (LTP)). Purpose of modifications: Introduction of the DTI with CEI socket. - Modification to (Connection of one or more simple terminals in the same subscriber terminal installation). Purpose of modification: In the 1 st paragraph, replacement of «90m» by «45m». Line termination point (LTP)